Jefferson County was created by the Alabama legislature on 1819 Dec. 13. It was named in honor of Thomas Jefferson. The county is located in the north-central portion of the state, on the southern extension of the Appalachians, in the center of the iron, coal and limestone belt of the South. Jefferson County is bordered by Blount, Bibb, St. Clair, Shelby, Tuscaloosa, and Walker counties. It encompasses 1,119 square miles. The county seat was at Carrollsville from 1819-21, at Elyton from 1821-73, and since 1873 has been at Birmingham, which was named for England's iron and steel center in Warwickshire.
Jefferson County is the most populated and principal county in the Greater Birmingham area.